1. Field of the Invention
The present invention relates to a seat belt assembly for restraining the body of an occupant seated in a seat of an automobile or an airplane in the seat at the time of emergency.
In addition, the present invention also relates to a seat belt assembly provided with a through anchor having a webbing sliding contact surface and a method for producing the through anchor.
2. Description of the Related Art
Conventionally, there exists a three-point seat belt assembly using continuous webbing as a seat belt assembly for restraining an occupant of a vehicle in a seat in which he or she is seated.
Referring to FIG. 52, in a seat belt assembly 910, one end of a webbing 911 is wound and stored in a retractor 912 in such a manner as to be freely pulled out thereof. The other end thereof is locked to an anchor plate 914 via a through anchor 915 which functions as a webbing guide. The anchor plate 914 is supported rotatably at a lower portion of a center pillar 913. A through tongue 916 disposed between the anchor plate 914 and the through anchor 915 is engaged with a buckle 918 which is provided so as to erect from a vehicle body in the vicinity of the seat 917. With this engaging, the webbing 911 restraints an occupant (not shown) in a seat 917.
In addition to the through anchor 915 and the through tongue 916, the seat belt assembly 910 also has a through belt(not shown), a webbing guide at an exit of the retractor and the like, which all function as a webbing guide for guiding the webbing 911.
An elongated hole-shaped belt slot (a gap through which the webbing passes) is formed in the respective webbing guides. The webbing 911 is brought into sliding contact with the belt slot when the webbing 911 is allowed to pass therethrough, whereby the belt slot guides the webbing 911.
In order to secure good retractability of the webbing 911 and good operating feeling when the webbing 911 is pulled out, the friction resistance generated where the webbing 911 is in sliding contact with the belt slot should be maintained as low as possible. To cope with this, a coating resin is applied to make the shaped surface of the belt slot smooth, or as described, for instance, in the U.S. Pat. No. 4,582,340, a low friction material is applied to treat the surface of the belt slot.
Of those webbing guides, the through anchor 915 can be constructed, for example, by applying a coating resin to a metal insert through insert molding. The through anchor 915 must bear a load generated when vehicles collide with each other. To make this possible, a mechanical strength, which is sufficient to prevent the deformation thereof when a load is applied thereto, is required for the coating resin. In general, however, a resin material having a high mechanical strength cannot provide good slidableness relative to the webbing 911, whereas a low friction material having a low friction coefficient and providing good slidableness cannot provide the sufficient mechanical strength. Thus, it has been difficult to improve the slidableness relative to the webbing 911 while maintaining the required mechanical strength.
In addition, with the through anchor formed through insert molding of the metal insert with the coating resin, depending on a molding material used, the frictional resistance between the through anchor and the webbing increases while a user repeatedly uses the seat belt assembly in the market place, and therefore the retraction and extension of the webbing gets heavy with time (deterioration with age in sliding contact performance). Extremely speaking, there may be caused a problem that the webbing is not completely retracted into the retractor when the seat belt is not fastened (when the through tongue is disengaged).
To solve these problems, for example, Japanese Utility Model Examined Publication No. Sho. 57-36209 discloses a webbing guide for reducing the sliding resistance between a webbing and therewith.
In other words, this webbing guide is constructed by axially cutting away a pipe formed of a low friction material along one side thereof such that the width of the cut becomes smaller than the outside diameter of a core metal and placing the pipe so cut over the core metal by making use of the resiliency of the pipe. The webbing is hooked and wound around the outer circumference of the pipe placed over the core metal.
With the webbing guide described in the above-mentioned Japanese Utility Model Examined Publication No. Sho. 57-36209, there exists a problem that tremendous manpower and time are required for placing the pipe over the core metal and securing a required accuracy in dimensions of respective structural portions, resulting in increased costs.
In addition, when a large magnitude of force is applied to the pipe when the webbing is brought into sliding contact therewith, the pipe may rotate relative to the core metal and moreover there may be a risk of failure of the pipe.
Moreover, as a through anchor having a webbing sliding contact surface constituted by a metallic surface, there is provided a through anchor formed by pressing a piece of sheet metal so as to form a webbing pass-through hole, a webbing sliding contact surface and a bolt attachment hole therein.
For example, the U.S. Pat. No. 4,618,165 describes a deflecting device 980 (a through anchor 980) formed through a single pressing process as shown in FIG. 53. In the deflecting device 980, a base plate 982 having a bolt attachment hole 981 formed therein is surrounded by a fitting frame 983 and a webbing pass-through hole 984 and a webbing sliding contact surface 985 are formed in a lower portion of the fitting frame 983.
With the conventional through anchor 980 described above, since the webbing sliding contact surface 985 is constituted by the metallic surface, the friction between the webbing and the webbing sliding contact surface can be maintained low, thereby making it possible to obtain good retractability and durability of the webbing.
With the aforesaid through anchor 980, however, there are caused some problems: the pressing process becomes complicated; the cost is increased; and configurations that can be obtained are limited.
In addition, there is caused another problem that at least a part of the external surface of the through anchor 980 needs to be covered with such as a cover constituted by a resin molded article in view of suitability for attachment to the vehicle body, and this also serves to increase the cost.
Accordingly, a first object thereof is to provide a seat belt assembly providing superior sliding contact between a webbing guide and webbing while having a simple construction.
In addition, a second object of the invention is to provide a seat belt assembly provided with a through anchor and a method for producing the through anchor, the through anchor being free from limitation to configurations that can be obtained while good webbing retractability and durability are obtainable, whereby reduction in cost is aimed at by making the production thereof easy.
The first object of the invention is attained by a seat belt assembly comprising webbing for restraining the body of an occupant in a seat and a webbing guide adapted to be brought into sliding contact with the webbing for guiding the webbing, wherein the webbing guide is constructed by insert molding a metal insert into a coating resin, and wherein the metal insert so molded is exposed at at least a part of a portion of the webbing guide where the webbing guide is brought into sliding contact with the webbing.
According to the above construction of the invention, the webbing restraints the body of an occupant which is guiding while being brought into sliding contact with the webbing guide. The metal insert is exposed at at least a part of the portion of the webbing guide where the webbing guide is brought into sliding contact with the webbing, whereby superior sliding contact between the webbing guide and the webbing can be secured.
Additionally, the first object of the invention is also attained by a seat belt assembly comprising webbing for restraining the body of an occupant in a seat and a webbing guide adapted to be brought into sliding contact with the webbing for guiding the webbing, wherein the webbing guide is constructed by insert molding a metal insert into a coating resin and winding a metal plate around a portion of the webbing guide where the webbing guide is brought into sliding contact with the webbing, and wherein at least a part of the portion of the webbing guide where the webbing guide is brought into sliding contact with the webbing constitutes a metal surface finished with a plated metal or stainless steel.
According to the above construction of the invention, the webbing, restraints the body of an occupant which is guiding while being brought into sliding contact with the webbing guide. At least a part of the portion of the webbing guide where the webbing guide is brought into sliding contact with the webbing constitutes the metal surface finished with the metal which is plated on the surface thereof or stainless steel, and therefore the adhesion of foreign particles is suppressed and deterioration with age in sliding contact with the webbing is reduced, whereby good sliding contact can be maintained.
Here, raised as the above plated metal surface are a metal surface constructed by winding another metal plate which is plated on the surface thereof around the coating resin for sliding contact with the webbing, or a metal surface constructed by exposing a part of the metal insert molded with the coating resin therefrom and plating the exposed portion (or the whole metal insert) for sliding contact with the webbing.
As plating, while any of chrome, nickel, electroless plating, cobalt, tin-cobalt and rigid chrome plating is preferred, any other plating may be used as long as the adhesion of foreign particles is suppressed.
Furthermore, the first object of the invention is also attained by a seat belt assembly comprising webbing for restraining the body of an occupant in a seat and a webbing guide adapted to be brought into sliding contact with the webbing for guiding the webbing, wherein the webbing guide is constructed by insert molding a metal insert with a coating resin and wherein a plated resin cover is fitted over a portion of the coating resin where the webbing is brought into sliding contact so that the surface of the resin cover constitutes a webbing sliding contact surface.
According to the above construction of the invention, the webbing, restraints the body of an occupant in a seat which is guiding while being brought into sliding contact with the webbing guide. The plated resin cover is fitted over the portion of the webbing guide where the webbing guide is brought into sliding contact with the webbing. The surface of the resin cover constitutes the webbing sliding contact surface.
Accordingly, since the adhesion of foreign particles is suppressed by the plating on the resin cover, there is no deterioration with age in sliding contact with the webbing, whereby good sliding contact can be maintained.
Here, raised as a specific material for the resin cover are POM, nylon, ABS or the like, and it is preferable to use a plating grade item when using any of them. Raised as representatives of the plating grade item are Lennie E40 polyamide resin by Mitsubishi Engineering Plastics Co., Ltd. and Toyobo Nylon-6 (T-777-02, T-779) by Toyobo Co., Ltd.
As the type of plating, rigid chrome plating is preferred, but any other type of plating may be used including chrome, nickel, electroless, cobalt and tin-cobalt plating.
Moreover, the second object of the invention is attained by a seat belt assembly provided with a through anchor having a webbing sliding contact surface which is constituted by a metal surface, the through anchor comprising a metal insert having a webbing pass-through opening, a coating resin having a pair of fitting grooves formed in an external surface thereof and adapted to cover the periphery of the webbing pass-through opening in the metal insert and a metal plate inserted in the webbing pass-through opening in the metal insert along a direction in which the webbing is allowed to pass therethrough, adapted to fit to an external surface configuration of the coating resin on the periphery of a lower edge portion of the webbing pass-through opening and fitted in the respective fitting grooves formed in the coating resin at edge portions thereof in the webbing pass-through direction to thereby be secured to the external surface of the coating resin.
In the through anchor according to the invention, the metal plate is inserted in the webbing pass-through opening of the metal insert along the direction in which the webbing is allowed to pass through the opening. The metal plate so inserted is adapted to ft to the external surface of the coating resin on the periphery of the lower edge portion of the webbing pass-through opening. Then the edge portions of the metal plate so adapted in the webbing pass-through direction are fitted respectively in the fitting grooves of the coating resin to thereby be secured to the external surface of the coating resin.
Thus, the webbing sliding contact surface is constituted by the external surface of the metal plate.
In the above construction, it is preferable to construct the respective fitting grooves of the coating resin as a space expanding inwardly and to provide, at the distal ends of the edge portions of the metal plate in the webbing pass-through direction, pawl portions which are each formed into serrations extending along a direction substantially normal to the webbing pass-through direction.
According to this construction, there is no likelihood that the edge portions of the metal plate in the webbing pass-through direction are dislocated from the respective fitting grooves, and in addition, when fitted in the fitting grooves, the pawl portions bite into the coating resin, the pawl portions being each formed into serrations extending along a direction substantially normal to the webbing pass-through direction.
Accordingly, the metal plate is securely fixed to the external surface of the coating resin.
Preferably, the through anchor of the seat belt assembly is produced using a method for producing a through anchor having a webbing sliding contact surface constituted by a metal surface, comprising the steps of coating the periphery of a webbing pass-through opening formed in a metal insert with a coating resin and forming a pair of fitting grooves in an external surface of the coating resin, thereafter inserting a metal plate in the webbing pass-through opening in the metal insert along a direction in which webbing is allowed to pass through the opening and causing the metal plate to fit to the external surface configuration of the coating resin on the periphery of a lower edge portion of the webbing pass-through opening, and fitting the edge portions of the metal plate in the webbing pass-through direction in the respective fitting grooves so that the metal plate is secured to the external surface of the coating resin.
In the method for producing a through anchor according to the invention, first, the periphery of the webbing pass-through opening formed in the metal insert is coated with the coating resin and forming the pair of fitting grooves in the external surface of the coating resin.
Next, the metal plate is inserted into the webbing pass-through opening of the metal insert along the direction in which the webbing is allowed to pass through the opening, and the plate is allowed to fit to the external surface of the coating resin on the periphery of the lower edge portion of the webbing pass-through opening.
Thereafter, the edge portions of the metal plate in the webbing pass-through direction are fitted in the respective fitting grooves of the coating resin to thereby secure the metal plate to the external surface of the coating resin.
In the above through anchor producing method, preferably projections provided on a fixture in such a manner as to project therefrom are allowed to pass through guide holes formed in the edge portions of the metal plate in the webbing pass-through direction. In this state, the respective edge portions of the metal plate are pressed inwardly of the fitting grooves of the coating resin by means of the fixture, whereby the edge portions of the metal plate in the webbing pass-through direction are respectively fitted in the respective fitting grooves of the coating resin while the metal plate is allowed to fit to the external surface of the coating resin on the periphery of the lower edge portion of the webbing pass-through opening.
The reason for this is because the metal plate can be secured to the external surface of the coating resin in a simple fashion while preventing the positional deviation of the metal plate by using the fixture.